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3 years ago

4 HF(g)+SiO2(s) → SiF4(9)+2 H2O(9) Is the Si oxidized or reduced?

Chemistry

1 answer:

Airida [17]3 years ago

8 0

Answer:

Si is reduced since it loses the oxygen atom

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A helium-filled balloon at 310.0 K and 1 atm, contains 0.05 g He, and has a volume of 1.21 L. It is placed in a freezer (T = 235

trapecia [35]

Answer : The value of $\Delta E$ of the gas is 2.79 Joules.

Explanation :

First we have to calculate the moles of helium.

$\text{Moles of helium}=\frac{\text{Mass of helium}}{\text{Molar mass of helium}}$

Molar mass of helium = 4 g/mole

$\text{Moles of helium}=\frac{0.05g}{4g/mole}=0.0125mole$

Now we have to calculate the heat.

Formula used :

$q=nc_p\Delta T\\\\q=nc_p(T_2-T_1)$

where,

q = heat

n = number of moles of helium gas = 0.0125 mole

$c_p$ = specific heat of helium = 20.8 J/mol.K

$T_1$ = initial temperature = 310.0 K

$T_2$ = final temperature = 235.0 K

Now put all the given values in the above formula, we get:

$q=nc_p(T_2-T_1)$

$q=(0.0125mole)\times (20.8J/mol.K)\times (235.0-310.0)K$

$q=-19.5J$

Now we have top calculate the work done.

Formula used :

$w=-p\Delta V\\\\w=-p(V_2-V_1)$

where,

w = work done

p = pressure of the gas = 1 atm

$V_1$ = initial volume = 1.21 L

$V_2$ = final volume = 0.99 L

Now put all the given values in the above formula, we get:

$w=-p(V_2-V_1)$

$w=-(1atm)\times (0.99-1.21)L$

$w=0.22L.artm=0.22\times 101.3J=22.29J$

conversion used : (1 L.atm = 101.3 J)

Now we have to calculate the value of $\Delta E$ of the gas.

$\Delta E=q+w$

$\Delta E=(-19.5J)+22.29J$

$\Delta E=2.79J$

Therefore, the value of $\Delta E$ of the gas is 2.79 Joules.

3 0

3 years ago

Can someone pls help me

lesya [120]

Yes bro I gotchu now gimme da thanks and da answer is urs

8 0

3 years ago

Regular copyright is more restrictive than any other kind of license. true or flase

GREYUIT [131]

The correct answer is true

8 0

3 years ago

Using the thermodynamic information in the ALEKS Data tab, calculate the standard reaction entropy of the following chemical rea

Lapatulllka [165]

Answer:

-122 J/K

Explanation:

Let's consider the following balanced reaction.

N₂(g) + 2 O₂(g) ⇒ 2 NO₂(g)

We can calculate the standard reaction entropy (ΔS°) using the following expression.

ΔS° = Σ ηp × Sf°p - Σ ηr × Sf°r

where,

η: stoichiometric coefficients of products and reactants

Sf°r: entropies of formation of products and reactants

ΔS° = 2 mol × 240.06 J/K.mol - 1 mol × 191.61 J/K.mol - 2 mol × 205.14 J/K.mol

ΔS° = -121.77 J/K ≈ -122 J/K

8 0

2 years ago

Which family of elements can be found in the area marked B

postnew [5]

Answer:

A) Alkaline Earth Metals

Explanation:

Area Marked A would be Alkali Metals

Area Marked B would be Alkaline Earth Metals

Area Marked C would be Transition Metals

Area marked H would be Halogens

3 0

3 years ago